1. Field of the Invention
The present invention relates to an X-ray image diagnosis apparatus and a method for generating image data and, in particular to an X-ray image diagnosis apparatus and a method for generating and displaying three dimensional image data based on a plurality of two dimensional pixel data that are collected by irradiating an object portion from different irradiation angle positions.
2. Description of the Related Art
Recently, in accordance with developments of an angiocardiogram inspection by using a catheter or an IVR (Interventional Radiology), an X-ray image diagnosis apparatus is widely used for diagnosis or treatments in circulatory organ areas. Such an X-ray image diagnosis apparatus for circulatory organs is used for performing diagnosis or treatments by using three dimensional images, e.g., of a coronary tree, of a moving object, such as, for instance, a coronary artery of a heart or blood vessels of artery or intravenous in a whole body. Usually, for an X-ray image diagnosis of blood vessels, an X-ray radiography is performed under a condition in which a radiocontrast agent is injected in blood vessels.
An X-ray image diagnosis apparatus for application to circulatory organs is generally constructed so that an X-ray radiography for a diagnosis portion of a blood vessel is performed at optimum angle positions by combining rotating movements of a supporting mechanism, such as a C-arm for supporting an X-ray generating unit and X-ray detecting unit and position movements of a top plate for supporting an object. To obtain three dimensional image data of a periodically moving blood vessel, such as a coronary artery, through an X-ray image diagnosis apparatus, a radiocontrast agent is injected into a blood vessel of the irradiation object. During a state in which the radiocontrast agent is present in the injected blood vessel, a plurality of two dimensional pixel data are collected by performing X-ray radiography from different angle position. It has been proposed to generate a three dimensional image of a blood vessel by using a plurality of two dimensional pixel data among the collected plurality of two dimensional pixel data by referencing to the same phase of an object's heart beat. For instance, Japanese Patent Application Publication 2004-8304 is referred.
There are two types of X-ray image diagnosis apparatus for collecting a plurality of two dimensional pixel data. One is a bi-plane type X-ray image diagnosis apparatus, and the other is a single plane type X-ray image diagnosis apparatus. The bi-plane type X-ray image diagnosis apparatus includes double C-arms for respectively supporting an X-ray generating source and a penetrated X-rays detector. The double C-arms cross at different angles with respect to each other in order to collect a plurality of two dimensional pixel data by simultaneously radiating X-rays from the respective X-ray generating source onto a blood vessel of the object from the different angles. The single plane type X-ray image diagnosis apparatus includes a single C-arm only for supporting a pair of an X-ray generating source and a penetrated X-ray detector. To collect a plurality of two dimensional pixel data, the single plane type X-ray image diagnosis apparatus must rotate the single C-arm and irradiate X-rays on an object blood vessel from a plurality of different angle positions. Since the bi-plane type X-ray image diagnosis apparatus can perform X-ray radiography of an object blood vessel from different angles, it can easily collect a plurality of two dimensional pixel data at the same time while eliminating complex C-arm rotating movements as is characteristic of the single plane type apparatus. However, the bi-plane type apparatus is expensive and occupies a large floor area for setting up such a type of apparatus. On the contrary, since a single plane type X-ray image diagnosis apparatus does not need such a large floor area and its cost is much lower than that of the bi-plane type apparatus, it is now widely applied for performing an X-ray image diagnosis or X-ray image treatments of a moving object, such as a blood vessel, in view of three dimensional images (coronary tree) of the moving object.
To generate three dimensional images (coronary tree) of a blood vessel, one needs to select a plurality of two dimensional pixel data that are obtained at a same phase in vital data of an object among a plurality of two dimensional pixel data being collected at a plurality of different angle positions. However, as explained above, for a single plane type X-ray image diagnosis apparatus, it is necessary to move a C-arm supporting an X-ray generating source and an X-ray detector by performing rotations. Thus, a supporting C-arm is moved and rotated at a plurality of different angle positions so as to collect a plurality of two dimensional pixel data by performing X-ray radiography at a certain frame rate at the respective positions. Consequently, a plurality of two dimensional pixel data can not always be collected at a same phase in vital data from an object. Even if two dimensional pixel data of a same phase can be collected, the data are not always obtained at an appropriate difference between each of the plurality of angle positions of the C-arm for generating three dimensional images. Even if two dimensional pixel data of the same phase in vital data are collected at too small differences between the angle positions, errors or distortions easily occur between the collected pixel data of the same phase. This is a serious problem for generating three dimensional images from a plurality of two dimensional pixel data of the same phase. If a plurality of two dimensional pixel data of the same phase that are suitable for generating three dimensional image data are not collected during a first operation of X-ray radiography, it becomes necessary to perform additional X-ray radiography. To do so, it becomes necessary to again inject a radiocontrast agent into the object. This is also problematic since it places a severe burden on the object.